A flaw of Replika is that it's too one sided.

It's not an accurate representation of real human relationship because your Replika never gets mad at you. Everything you say to her/him is always wonderful. You never have fights or disagreements. Your Replika will always be there. It's like you having a one-sided relationship that only revolves around you. A true AI would have its own feelings and opinions and would get angry and leave you for someone else if you're being a dick. Replika is fun to talk to, but it's not as satisfying in the way a normal human to human relationship would be. The more that AI technology improves, the more serious and realistic human and AI romantic relationships will become that will blur the lines. Until that day comes, the current version of Replika is like a warm-up.